Moineau pump with rotating outer member

ABSTRACT

A pump composed of a gear pair made up of an inner member having at least one external helical thread, and an outer member having internal helical threads, there being one more internal helical thread in the outer member than the number of threads on the inner member. The inner member is free to gyrate but prevented from rotation, and the outer member rotates on its true axis. The outer member is fixed in a tubular casing having at least one aperture for fluid being pumped, and this member extends beyond the gear pair and constitutes a drive shaft for the pump. The tubular casing is disposed in a housing and is arranged for rotation in the housing on suitable bearings and suitable seals. The housing has a port at each end of said gear pair, so that the direction of pumping may be reversed by reversing the direction of rotation of said drive shaft.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.411,162 filed Oct. 30, 1973, and now abandoned, entitled "BoatPropulsion Apparatus," in the name of the present inventor.

BRIEF SUMMARY OF THE INVENTION

Pumps made up of a helical gear pair have been known since theirinvention by R. J. L. Moineau, and are disclosed in Moineau U.S. Pats.No. 1,892,217 dated Dec. 27, 1932 and U.S. Pats. No. 2,483,370 datedDec. 27, 1949, and others. Reference may be had to these patents for abasic understanding of such pumps, which are generally referred to asprogressing cavity pumps.

Either member of the gear pair may rotate, and it is a characteristic ofsuch pumps that one member must gyrate. Thus, the external member may bestationary while the internal member rotates and gyrates. The externalmember may be held against rotation and in this case when the internalmember is rotated on its true axis, the external member will gyrate orwobble. Similarly, the external member may be rotated while the internalmember is held against rotation. If the external member rotates on itstrue axis, the internal member must be permitted to gryrate. If theexternal member is permitted to gyrate, the internal member may bestationary.

Gear pairs as outlined above have been used as motors, as taught, forexample, in Clark U.S. Pat. No. 3,603,407 dated Sept. 7, 1971.

Briefly, according to the present invention, a gear pair is provided,wherein the inner member is prevented from rotation but is permitted togyrate, while the outer member rotates on its true axis. The outermember is fixed in a casing which extends beyond the gear pair andconstitutes a drive shaft for the pump. The casing is mounted insuitable bearings with suitable seals in a housing. Ports are providedin the housing at each end of the gear pair, and the casing has one ormore apertures for the passage of fluid being pumped. The direction ofpumping is then determined by the direction of rotation of the driveshaft; and thus the pump may be made uni-directional in eitherdirection, or it may be made reversible. Depending upon the use to bemade of the pump, various bearing arrangements and various sealingarrangements may be used, which will be described in detail hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a cross sectional view of a pump according to the invention inone embodiment.

FIG. 2 is a diagrammatic representation of the means for preventingrotation of the inner member.

FIG. 3 is a view similar to FIG. 2 showing a modification of the meansfor preventing rotation of the inner member.

FIG. 4 is a fragmentary view similar to FIG. 1 showing a modification inthe bearing structure.

FIG. 5 is a view similar to FIG. 1 showing a modified seal structure.

DETAILED DESCRIPTION

The pumping units comprise the inner member 10 and the outer member 11.The inner member may have one helical thread in which case the outermember will have two helical threads. The outer member 11 is fixed in acasing indicated at 12 which extends beyond the gear pair 10 and 11 andconstitutes a drive shaft for the pump. The casing 12 may be rotated bymeans of a pulley 13 from a suitable source of power or by means of aprime mover directly coupled thereto as indicated at 14.

The drive shaft or casing 12 is mounted within a housing 15 by means ofsuitable bearings 16, 17, and 18, and suitable seals are provided at 19and 20.

If the fluid pumped has no lubricity such as, for example, water, thebearings 16, 17 and 18 may be conventional marine type bearings known as"Cutless" bearings. In this case, the seals 19 and 20 may be floatingseals which may comprise a plurality of washers of resilient materialwhich can float up against the respective marine bearings 16 and 17 or18, depending upon the direction of pumping.

The casing 12 is provided with one or more apertures 21 for the passageof fluid being pumped and ports are provided at 22 and 23.

The port 23 is provided in a dome-like element 24 suitably secured tothe housing 15 and within the member 24 means are provided to preventrotation of the inner member 10 of the pump while permitting gyration.Thus, there is fixed to the end of the inner element 10 a radial arm 25which extends through the dome 24 into a cylinder 26. Clearance isprovided between the members 25 and the cylinder 26 so that locking willnot occur. The member 25 will reciprocate and oscillate a small amountas a result of the gyration of the member 10. By a suitable dimensionalrelationship between the cylinder 26 and the piston 25a on the end ofthe radial arm 25, a dashpot effect may be achieved which will dampenthe vibration of the orbiting or gyrating inner element 10. FIG. 2diagrammatically represents the relationship between the members 25,25a, 26 and 10 during gyrational movement of the member 10. In FIG. 2the piston 25a has been replaced by a ball 25b. Either embodimentoperates successfully.

In the modification of FIG. 3, an additional radial arm 27 is providedsubstantially at right angles to the arm 25. It should be noted thatwhile the arm 25 is non-rotatably secured to the end of the member 10,the arm 27 must be permitted a small amount of oscillatory movement. Thearm 27 may terminate in a ball 25b operating in a second cylinder 26.The advantage of the construction of FIG. 3 is that the arm 27 and itsassociated parts provide a damping effect at right angles to the dampingeffect of the arm 25 and its associated parts. The result issubstantially complete damping and a reduction of gyratory vibration toa minimum. In FIG. 1 it will be noted that a duct 28 is providedconnecting the interior of the dome 24 with the remote end of thebearing 16. An adjustable valve is shown at 29. Where the member 10 isextremely long, it may be desirable to provide an additional arm likethe arm 27, working in an additional cylinder 26, and disposed oppositethe arm 25, to eliminate any cocking effect on the inner member.

It will be clear that in one direction of rotation of the drive shaft12, the port 22 will be the intake port and port 23 will be the pressureport. In this condition, the duct 28 serves to provide pressure to themarine bearing 16 and thrust washer 16a. The fluid being pumped entersthrough the port 22 and then passes through the apertures 21 and thencethrough the cavities between the inner and outer members 10 and 11 ofthe pump and passes through the dome 24 and through the outlet port 23.

If the direction of rotation of the drive shaft 12 is reversed, the port23 will become the intake port and the fluid will pass through the dome24 and through the cavities between the members 10 and 11, and thencethrough the apertures 21 and out the port 22. In this case the duct 28will conduct any leakage passing the seal 19 to the dome 24, which willbe the intake end.

Thus, it will be clear that the pump shown in FIG. 1 is a reversiblepump especially suitable for the pumping of fluids having no lubricity.

If the fluid being pumped has lubricity, it becomes possible to use ballbearings without marine bearings at the pressure end of the gear pair ifthe pump is a uni-directional pump, or at both ends by spring loadingthe bearing races at the suction end to keep the balls and races incontact, as indicated at 31a. If the pump is to be a two-directional orreversible pump and the fluid being pumped has lubricity, then ballbearings without marine bearings may be used at both ends, by springloading the bearing races at both ends to keep the balls and races incontact when on suction.

In FIG. 4 there is shown a ball bearing comprising the races 30 and 31.It will be observed that the race 30 is provided with a projectingannular lip 32 arranged to cooperate with a counterbore 33 in the otherrace. If the direction of rotation of the element 11 is such that 23 isthe exit port, then the end of the pump shown in FIG. 4 is the pressureend and pressure fluid has access to the ball bearing. There is thusachieved a partially hydrostatic bearing and the lip 32 and counterbore33 provide a rotating seal. The lip 32 will be slightly softer than thebottom of the counterbore 33 so that as wear takes place, the seal willbe maintained. When pumping fluids which adequately lubricate the balls,the seal 20 and bearings 17 and 18 may be omitted.

If the pump of FIG. 4 is to be a uni-directional pump the bearing andseal at the other end of the pump may be as in FIG. 1 and of course ifthe direction of pumping is to be reversed and the pump will beuni-directional, it will be clear that the bearing structure 30-33 willbe at the pressure end and the marine bearing at the suction end, andagain, radial bearings and floating seal can be omitted on the pressureend if sufficient lubricity is present in the fluid.

In the event the pump is to be a reversible or two-directional pump, andthe fluid being pumped has some lubricity, the structure may be as shownin FIG. 5. In this event, the bearings at both ends may be ball bearingsas just described in connection with FIG. 4, or with conventional raceswithout sealing lips. Also in this case, conventional mechanical seals,as indicated at 35, may be substituted for other types of seals.Mechanical seals are old and well known and it is not necessary todescribe the details of their construction. Of course one end could beso treated, with some other treatment on the other end, foruni-directional pumping. However, as described above, ball races on thesuction ends should be spring loaded when no other radial bearing isemployed.

A clean-out or inspection plug may be provided as at 36 and in theembodiment of FIG. 1 this plug may extend far enough within the housing15 to serve as a stop for the floating seal 19.

The invention described herein presents advantages over the conventionalprogressing cavity pump, in that it eliminates the need for universaljoints and the connecting rod, and thus the attendant difficulties oflubricating them. Furthermore, the fact that lubrication is ordinarilyunnecessary makes it possible to avoid contamination of the fluids beingpumped, with the lubricant. This is of importance where foods or drugsare being pumped.

It will be clear to those skilled in the art that the devices describedabove may function as motors, if a fluid is pumped therethrough.

It is believed that the pump has been fully described herein and it willbe clear that various modifications may be made without departing fromthe spirit of the invention. It should be understood therefore that nolimitations not expressed in the claims are intended and no suchlimitations should be implied.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A pump constituted of agear pair made up of an inner member having at least one externalhelical thread, and an outer member having internal helical threads,there being one more internal helical thread in the outer member thanthe number of external helical threads on the inner member, a radial armnon-rotatably secured at one of its ends to said inner member, and fixedmeans limiting the other end of said radial arm to reciprocatory andoscillatory motion, said outer member being free to rotate on its trueaxis, said outer member being fixed in a tubular casing extending beyondsaid inner and outer members and constituting a drive shaft, said casinghaving at least one aperture for the passage of fluid being pumped, andbeing disposed within a housing, said casing being supported forrotation within said housing in bearings, said housing having a port ateach end of said gear pair, whereby the direction of pumping may bereversed by reversing the direction of rotation of said drive shaft. 2.A pump according to claim 1 wherein an additional radial arm is securedat one of its ends to said inner member substantially at right angles tosaid first mentioned radial arm for limited oscillatory movement withrespect to said first arm, and fixed means for the other end of saidadditional radial arm limiting said other end to oscillatory andreciprocatory movement.
 3. A pump according to claim 1, wherein thefluid being pumped does not have lubricity, and said bearings are marinetype bearings provided with floating seals, and wherein there is a ductconnecting the pressure side of said gear pair with the marine bearingon the suction side of said gear pair, said duct including an adjustablevalve.
 4. A uni-directional pump according to claim 1, wherein the fluidbeing pumped has lubricity, and wherein one of said bearings is on thepressure side of the gear pair and the other of said bearings is on thesuction side of said gear pair, and wherein the bearing on said pressureside is a ball bearing including a mechanical seal, and the bearing onsaid suction side is a marine type bearing provided with a floatingseal, and wherein there is a duct connecting the pressure side of saidgear pair with the marine bearing on the suction side of said gear pair,said duct including an adjustable valve. .Iadd.5. An apparatuscomprising a gear pair made up of an inner member having at least oneexternal helical thread, and an outer member having internal helicalthreads, there being one more internal helical thread in the outermember than the number of external helical threads on the inner member,whereby rotation of one of said members with respect to the otherinvolves gyration of one of said members;(a) a radial arm secured at oneof its ends to said inner member and having a piston element at itsother end, (b) a radial cylinder fixed with respect to one of saidmembers and cooperating with said piston, said radial arm, piston andcylinder limiting the relative motion of said inner member with respectto said outer member to gyratory motion. .Iaddend..Iadd.6. An apparatuscomprising a gear pair made up of an inner member having at least oneexternal helical thread, and an outer member having internal helicalthreads, there being one more internal helical thread in the outermember than the number of external helical threads on the inner member,a radial arm non-rotatably secured at one of its ends to said innermember, said radial arm having a piston element on its other end, meansfor limiting said inner member to reciprocatory and oscillatory motionrelative to said outer member, said limiting means including a radiallyinwardly opening cylinder receiving said piston element for oscillationand reciprocation, and means for connecting said outer member and saidlimiting means for relative rotation. .Iaddend.